When it comes to Autism in children there are different levels of autism that a child can have.
Some children with less severe autism may potty train just fine as early as 18 months of age or 2 years old while other children who have a more severe form of autism may be harder to potty train and may take as long as 4 years to even 8 to 10 years old before they go to the toilet and not need a diaper.
I babysat an 11 year old boy who still needed to wear diapers all the time until he turned 13 years old because he had a more severe form of autism.
His autism was not the most severe but it did make it harder for him to toilet train and he was struggling with toilet training until he turned 13 years old and then finally started using the toilet.
He's 15 now and still wears diapers when away from home and at night for bed wetting but during the day he's pretty good at using the toilet now although he still sometimes forgets and pees his pants.
Some people may have a slight version of autism where it makes them suffer from anxiety, not make eye contact, they may only talk to certain people etc.
That is known as high functioning autism.
There's no actual known cause of autism but it is thought that when babies get their vaccines that the vaccines could lead to autism and aspergers syndrome later on in life.
If your child has autism they may need to wear diapers longer than those who don't have autism and having autism can make it harder for a child to function later on in life.
Kids who suffer from either severe autism or less severe autism are usually also pretty shy and get bullied more often than those who do not.